Biggest Surprises and Disappointments of the First Half: Pitchers

Earlier this week, we took a look at some of the hitters who had both the most surprising and disappointing performances in the first half. Today, we will do the same with pitchers, and look deeper into their numbers to try to predict what we can expect from them in the second half.

Taking a quick look at Jason Vargas’ ERA estimators, such as FIP and xFIP, one can see that his 2.62 ERA is clearly outperforming his peripherals. His K% of 18.2% is actually down over 5 percent from his 2016 mark, and his K%-BB% is also down significantly. His low ERA in the first half appears to be mostly due to a high LOB% of 84.7% (fourth highest in baseball), and a low HR/FB ratio of 7.9%. Both of those stats tend to regress towards their averages of around 70-72% and 10% respectively (although it should be noted that HR/FB ratios appear to be trending upward in 2017, compared to past seasons). Once those stats regress, Vargas should go back to being the serviceable, yet unspectacular pitcher he has been throughout his career.

Severino’s peripherals speak for themselves, as his FIP and xFIP are actually lower than his ERA. His 28.4% K% is the eighth best mark in baseball, and his K%-BB% of 22.3% ranks as the seventh best. Along with a very respectable 6.2% BB% and the fastest average fastball velocity in baseball at 97.6 mph, Severino is clearly having the type of breakout season that many predicted he would have when he was a top prospect in the minors. I would expect Severino to continue his strong performance, and considering that he is only 23 years old, he may even improve.

Jimmy Nelson is a hard thrower whose strikeout totals never reached the levels expected of someone with his velocity. He has the sixteenth highest average fastball velocity in baseball at 94.7mph (which happens to be tied with Max Scherzer), but this is not a significant increase in velocity over past seasons where he posted only average strikeout rates. However, in the first half Nelson’s K% has jumped almost 9% from last year, from 17.4% to 26.1%, which is the fifteenth highest mark in baseball. To go along with an impressive BB% of 6%, and K%-BB% of 20.1% (thirteenth best in baseball), Nelson looks like he has made the jump into a top of the rotation caliber starter. One can see that his FIP (3.17) and xFIP (3.30) are very close to his ERA (3.30, same as his xFIP) showing that his ERA is right around where it should be. If he can maintain most of his gain in strikeouts without increasing his walks or HRs allowed, Nelson could be expected to sustain his first half performance.

Disappointments:

When looking at Julio Teheran’s first half struggles, his uncharacteristically high 4.79 ERA is the a very noticeable deviation from years past . Unfortunately, his ERA estimators of FIP (5.49) and xFIP (5.25) are even higher than his actual ERA, demonstrating that his ERA is actually lower than his peripherals suggest they should be. Teheran’s poor performance can be explained by the dreadful combination of a decreasing K% (sitting at 16.7%, which is down over 5% from 2016) and an increasing BB% (sitting at 8.9%, which is up 3.5% from 2016). Those two trends have led him to produce a K%-BB% of 7.8%, which is the eleventh worst mark in baseball amongst starting pitchers.

Looking even closer into Teheran’s numbers, we can see that his average fastball velocity of 91.7 mph has not significantly decreased from his previous seasons. Neither has his batted ball profile, as his GB/FB ratio is almost identical to his 2016 mark. Opposing batters’ Contact% against Teheran has gone up 2.6% from last year, and his SwStr% has dropped 1.6%, but even those differences shouldn’t be enough to explain the drastic decline in performance he has suffered in the first half.

Since he is only 26, one would hope that Teheran would be able to turn around his season. However, his substantial decrease in Ks and increase in BBs would need to be corrected in order for him to resume his previous spot amongst the better young starters in the sport.

Entering 2017, Johnny Cueto had not had an ERA above 3.64 in any season in this entire decade (he posted a 4.41 ERA back in 2009), and has had an ERA under 3 in five of the last six seasons. His remarkable consistency entering 2017 has made his poor results even more surprising, especially since he is only 31 and could have easily been expected to keep up his strong performance for a few more seasons. But at the all star break, Cueto has a very unimpressive 4.51 ERA. To make matters worse, he is not just having bad luck, as his ERA estimators (4.73 FIP and 4.41 xFIP) are roughly around the same mark as his actual ERA. This shows that his high ERA is in the neighborhood of where it should be so far.

Cueto’s K% has decreased since last year (down from 22.5% in ’16 to 20.3% this year) and his BB% has increased (up from 5.1% in ‘16 to 7.9% this year), which is never a good combination. This has led to his K%-BB% dropping 5 percentage points, all the way down to 12.4%. Cueto also seems to be allowing a lot more line drives (he currently has a career high LD% of 25.3%). Additionally, opposing batters have hit far fewer ground balls against him, as his GB% of 39.6% is his lowest since his rookie season, and down more than 10% from his 2016 mark. Also, 35.2% of balls hit off of him have been hard hit (per Fangraphs), which is a career high and up 8% from 2016. It seems as if some of this may be due to decreased velocity, as his average fastball velocity is at a career low 91.9 mph. However, this is only down 0.7 mph since last year, which shouldn’t be enough of a difference to make such a large impact on his performance.

Cueto’s HR/FB ratio has nearly doubled from 8.4% to 16.1%, and if that regresses back down towards league average, Cueto’s stats will almost certainly improve to some degree. However, as evidenced by his 4.41 xFIP, which adjusts for HR/FB ratios, there is still much more that needs to change for Cueto’s performance to rebound. Many of his peripherals seem to have declined so far this season, and even though some of the declines have only been modest, the totality suggests that he is simply becoming more hittable. At the age of 31 and having pitched a lot of innings over the past several seasons, Cueto may be entering the decline phase in his career. However, if he can improve his command slightly, he may still be able to be an average starter in the second half.

Tanaka’s poor first half can be easily explained by his 22.5% HR/FB, which is tied for the worst mark in baseball. The impact that this unusually high HR/FB ratio has had on his stats is shown in his xFIP, which adjusts for HR/FB ratio by assuming a league average rate. At 3.88, his xFIP is much better than his unsightly 5.47 ERA. Tanaka’s K% is actually up from 2016, and is sitting at an impressive 23.2% mark, and his 17.1% K%-BB% ranks twentieth out of 74 starting pitchers who qualify. With better luck I expect Tanaka to rebound strongly in the second half, and perform similarly to how he has from 2014-2016.

Steve is a diehard baseball fan (Lets Go Mets!) who lives in New Jersey. Originally from Brooklyn, hegraduated from Rutgers University with a Bachelor's Degree in Economics. Steve loves to focus on the sabermetrics side of baseball. He is also an avid music listener, and is always willing to debate pressing topics on Twitter.